1. Technical Field
The present disclosure relates to printed circuit boards, particularly to a method for manufacturing a printed circuit board.
2. Description of Related Art
Usually, a method for manufacturing a printed circuit board (PCB) includes the following processes. First, a PCB sheet including a PCB unit and an unwanted portion is provided. A plurality of contact pads is formed on the PCB unit. Imaginary boundary lines are defined between the PCB unit and the unwanted portion. Second, the PCB sheet is punched along the imaginary boundary lines. Thus, a plurality of through slots is forming between the PCB unit and the unwanted portion, and a plurality of interconnect links interconnect the PCB unit and the unwanted portion and separating the adjacent through slots. Third, a plurality of components is mounted on the contact pads of the PCB unit. Finally, the PCB unit is separated from the unwanted portion by punching the interconnect links, thereby obtaining a PCB.
However, a plurality of burrs will be formed at side portions of the PCB unit when punching the PCB sheet. When a nearest distance between a contact pad on the PCB unit and an edge of the PCB unit is less than 4 millimeters, the burrs may drop on the contact pad, resulting in a bad performance of the contact pad. A high-energy laser cutting method using a laser power of 8-15 watt is always applied instead of the punching method to prevent the generation of burrs. However, the surface of the contact pad may be oxidized by the high-energy laser beam because of the small nearest distance between the contact pad and the edge of the PCB sheet.
What is needed, therefore, is a method for manufacturing a printed circuit board that can overcome the above-described problems.